Image forming method recording medium and visible image reproducing medium

ABSTRACT

Provided an image forming method comprising the steps of; 
     forming electric charges on a recording layer by charging the recording medium comprising a conductive substrate and, provided thereon a photoconductive layer and a recording layer containing a polymeric liquid crystal compound, in this order; 
     irradiating, after the step of charging, said recording medium with a light corresponding to an image information to move electric charges to said photoconductive layer; and 
     writing said image information by means of changing a birefringence of the recording layer caused by said movement of electric charges.

this application is a continuation of application Ser. No. 08/118,360filed Sep. 9, 1993, now abandoned, which is a continuation ofapplication Ser. No. 07/723,947, filed Jul. 1, 1991.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming method making use of arecording medium comprising a recording layer containing a polymericliquid crystal compound, and more particularly to an image formingmethod that utilizes changes in alignment. It also relates to arecording medium that can be used in such an image forming method. Itstill also relates to a method of reproducing an image formed by such animage forming method.

2. Related Background Art

In a conventional digital electrophotographic system, informationsignals are recorded on a photosensitive member by operating "on-off"according to information signals while a semiconductor laser beam isscanned on the photosensitive member utilizing a polygonal mirror. Insuch a system, however, it is necessary to increase the output from alaser or deliver the output for a long time when a highly detailed imageis recorded or an image is recorded at a high speed, in particular, whenthe same image is recorded on a large number of sheets. Hence, a problemhas tended to arise on the durability of the laser itself. When imagesare continuously read in and recorded, the same image is repeatedly readin, and hence, a large load is applied to an optical scanner.

Moreover, it is difficult for semiconductor lasers to serve as laserlight sources for R, G and B corresponding with a color image, making itnecessary to provide a large-scale and complicated apparatus.

An analog recording system, on the other hand, is exemplified by asystem called a screen process in electrophotography, according to whichan intermediate image is obtained on an intermediate transfer medium inthe form of ion recording. This system, however, has an instabilityascribable to ion charging, and it has been impossible to obtain along-term memory performance.

A diazo recording system, having been in great demand because of a lowrunning cost, has also been disadvantageous in that no copy can be takenfrom a three-dimensional object and also disadvantageous in that it cannot handle color images.

As for image forming materials that are reversibly image-erasable andrepeatedly usable, having a possibility of being utilized asintermediate image holders, what can be considered useful arephotochromic materials, thermochromic materials, magnetic recordingmaterials, or liquid crystals sandwiched between glass plates.

However, use of a photochromic material as the intermediate image holderrequires irradiation on a photochromic layer in order to opticallyrecord an image on a photosensitive layer, since light is used as ameans of recording or erasing the image on or from the photochromicmaterial. This tends to cause changes in the photochromic layer orbrings about a problem in its durability.

Thermally reversible Ag₂ HgI₄ has been reported as a thermochromicmaterial. The material of this type, however, has no storage capability,and hence a heater must be always operated so that an image can beretained. There results not only in a large-scale and complicatedapparatus but also in a large power consumption.

As a further example, an intermediate image holder making use of aliquid crystal light valve is usually comprised of a low-molecularsmectic liquid crystal held between glass substrates, where a laserlight absorbing layer is provided in the cell and its homeotropicalignment is brought into a scattered state by heating with externalirradiation using a laser, thereby to obtain a contrast. This imageholder, however, can not be made to have a large area with ease onaccount of its structure, or has a complicated structure for anintermediate image holder because erasure is effected by electric-fieldalignment. It is also difficult to directly write an image using aheating-element head on account of the structure of the device. Takingaccount of the fact that the image holder can not be made to have alarge area, it is attempted to carry out the irradiation using ahigh-luminescence light source to project an enlarged image. There,however, is the disadvantage such that the irradiation deteriorates theintermediate image because of a poop heat stability.

To cope with such problems, polymeric liquid crystal compounds have beenproposed as materials capable of showing superior performances.

Recording mediums making use of polymeric liquid crystal compounds canbe exemplified by a thermal write memory disclosed in V. Shibaev, S.Kostromin, N. Plate, S. Ivanov, V. Vestrov and I. Yakovlev,"Thermotropic Liquid Crystalline Polymers. 14", Polymer Communications,Vol. 24, pp. 364-365.

However, because of a delay in response speed that concurrently occursas increase of molecular weight of the material, these have not been putinto practical use. To overcome such disadvantages, it has been proposedto achieve a higher speed by the use of a photoconductive layer(Japanese Patent Application Laid-open No. 64-7022).

The above prior art, however, in which the device is so constituted thata recording layer and the photoconductive layer are held between a pair0f electrode substrates, can not be satisfactory for the use of light asa means for writing, in resolution and contrast.

SUMMARY OF THE INVENTION

Accordingly, an object of the present invention is to provide an imageforming method that can achieve a stable recording and a good memoryperformance, in which light is utilized in order to increase sensitivityand by which an image can be formed in a high sensitivity even when thelight is in a low output.

Other objects of the present invention is to provide a recording mediumthat can be suitably used in such an image forming method, and also toprovide an image reproducing method capable of obtaining a high-contrastvisible image by the use of the image forming method.

The present invention provides a method of forming an image by a processcomprising the steps of;

forming electric charges on the recording layer by charging a recordingmedium which comprises a conductive substrate and, provided thereon aphotoconductive layer and a recording layer containing a polymericliquid crystal compound, in this order;

irradiating, after the step of charging, said recording medium with alight corresponding to an image information to move electric charges tosaid photoconductive layer; and

writing the image information by means of changing a birefringence ofthe recording layer caused by the movement of electric charges.

As another embodiment of the method, the present invention provides amethod of forming an image by a process comprising the steps of;

forming electric charges on said photoconductive layer by charging amedium "A" comprising a conductive substrate and provided thereon aphotoconductive layer;

irradiating, after the step of charging, said recording medium with alight corresponding to an image information;

bringing said medium "A" into contact with a medium "B" comprising aconductive substrate and provided thereon a recording layer containing apolymeric liquid crystal compound;

transferring, after the step of irradiating, the electric charges formedon the photoconductive layer of said medium "A", to the recording layerof said medium "B"; and

writing the image information by means of changing a birefringence ofsaid recording layer caused by the transfer of electric charges.

The present invention also provides a recording medium comprising aconductive substrate and, provided thereon a photoconductive layer, adielectric mirror and a recording layer containing a polymeric liquidcrystal compound, in this order.

The present invention still also provides an image reproducing methodcomprising the steps of

irradiating light on the recording medium in which an image has beenformed by the image forming method described above; and

displaying the image information on a screen or transferring the imageinformation to a photosensitive member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1D are each a cross section of the recording medium of thepresent invention.

FIGS. 2A to 2E and 3A to 3E each show a flow chart of the image formingmethod of the present invention.

FIG. 4, FIG. 5, FIGS. 6A and 6B, FIGS. 7A and 7B, FIGS. 8A and 8B, andFIGS. 9A and 9B illustrate Example 1, Example 2, Example 3, Example 4,Example 5 and Example 6 given later, respectively.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described below in detail.

The recording medium that can be preferably used in the image formingmethod of the present invention will be described first.

FIGS. 1A to 1D are each a cross section of the recording medium of thepresent invention.

In the drawings, reference numeral 101 denotes a substrate; 102, a lowerelectrode; 103, a photoconductive layer; 104, a dielectric mirror; 105,a recording layer; 106, a surface protective layer; and 107 (FIG. 1D),an aligning film. When the substrate 101 is made of a non-conductivematerial, a conductive layer is provided and the lower electrode isprovided thereon. When a conductive material such as a metal is used inthe substrate 101, the substrate 101 can serve as the lower substrate102 at the same time and hence it is unnecessary to additionally providethe lower electrode 102.

In the present invention, it is preferred to use this substrate 101 witha thickness of 10 μm to 2 mm. A substrate with a thickness less than 10μm is not preferable since the substrate may have an insufficientstrength to make it difficult to handle and lacking in durability. Asubstrate with a thickness more than 2 mm is also not preferable sinceit results in an increase in weight, etc. and also an increase in cost.The thickness may more preferably be in the range of 20 μm to 1.5 mm.

As materials used for the substrate, when it is made of a metal, it ispreferred to use aluminum, copper, brass, stainless steel, etc.

In view of the advantage that a large-area, flexible recording mediumcan be provided, it is preferred to use a polymer film, which can beexemplified by polyester films such as a polyethylene terephthalate filmand a polybutylene terephthalate film, and transparent films such as apolycarbonate film, a polyamide film, a polyimide film, a polymethylmethacrylate film, a methyl methacrylate/styrene copolymer film, apolystyrene film, a polypropylene film, a polyvinyl alcohol film, apolyvinyl chloride film, a polyvinylidene chloride film, apolyvinylidene fluoride film and a polyacrylate film. Examples thereofare by no means limited to these.

These films may be any of oriented films, having been subjected tomonoaxial stretching, biaxial stretching or the like, and non-orientedfilms, either of which can be used. A film having been stretched canhave a tensile strength improved twice to four times (in the case of,e.g., polyethylene terephthalate), and is one of preferred films.

In the case when such plastic films are used, the lower electrode 102 isformed by vacuum deposition or the like. For example, aluminum, gold orthe like may be vacuum-deposited in a thickness of about 100 Å to about5,000 Å to give a sufficiently good conductivity.

Next, the photoconductive layer 103 is formed on the substrate 101. Thephotoconductive layer used in the present invention may preferably becomprised of an inorganic material such as amorphous silicon or BSO(bismuth-silicon oxide) or CdS dispersed in a binder polymer, or anorganic photoconductive material dispersed in a binder polymer. When theorganic photoconductive material is used, the photoconductive layer mayhave a double-layer structure comprised of a charge transport layer anda charge generation layer.

In the present invention, the photoconductive layer should preferablyhave a thickness of 0.1 μm to 100 μm. A thickness less than 0.1 μm mayresult in an insufficient electrostatic capacitance produced whenelectric charges move. A thickness more than 100 μm may result in anunsatisfactory sensitivity, resolution and response speed. A morepreferred thickness is 1 μm to 50 μm.

In the present invention, after the formation of an image, the image canbe fixed, e.g., by selecting glass transition points over the imagekeeping temperature. Hence, the photoconductive layer can be madetransparent to light with wavelengths used when an image is transferredto a photosensitive member, so as to be used as a layer of atransmission type. In such an instance, the light with such wavelengthscan be reflected when the dielectric mirror 104 is used.

The dielectric mirror 104 need not be formed. When, however, a writingwavelength is approximate to a reading wavelength, the dielectric mirror104 may be formed so that writing light can be reflected from the sideon which the substrate as shown, for example, in FIG. 1, is provided andreading light can be reflected from the side on which the recordinglayer is provided. Formation and reproduction of images under suchconstitution can give a more preferred embodiment.

The recording medium of the present invention is characterized in thatthe recording layer 105 contains a polymer liquid crystal compound.

This polymer liquid crystal compound is capable of changing its surfacestate upon selection of any of the following states of alignment, and isusable in a state wherein any of the states of alignment has been fixedby controlling its glass transition point to be higher than roomtemperature. States of alignment:

(1) Isotropic phase.

(2) Nematic phase, vertically aligned.

(3) Nematic phase, horizontally aligned.

(4) Smectic phase, vertically aligned.

(5) Smectic phase, horizontally aligned.

The polymer liquid crystal compound used in the recording medium of thepresent invention may include the following: (In the following formulas(1) to (13), p=5 to 1,000 and 1≦n1<15. In formulas (14) to (17), p=5 to1,000, p1+p2=5 to 1,000, q=1 to 16, q1=1 to 16 and q2=1 to 16. Informulas (18) to (53), the asterisk * represents an optically activecarbon, and n2=5 to 1,000.) ##STR1##

The above polymer liquid crystal compounds may be used alone or can beused by mixture or copolymerization of two or more kinds. Alow-molecular liquid crystal compound may also be mixed so long asmemory stability is not damaged. In the present invention, the polymerliquid crystal compound refers to a compound wherein the repeating unitof a chain containing a mesogen group is not less than 5. Thelow-molecular liquid crystal compound refers to a compound wherein therepeating unit is 1. In this instance, in a polymer liquid crystalcomposition, the low-molecular liquid crystal compound may preferably beadded in an amount of 10% by weight to 80% by weight. Its addition in anamount less than 10% by weight may make insufficient the decrease inviscosity and improvement in alignment that are attributable to theaddition of the low-molecular liquid crystal compound. Its addition inan amount more than 80% by weight may result in a decrease in resistanceto bring about an undesirable response.

The low-molecular liquid crystal compound may also be used as a mixtureof two or more kinds.

Examples of the low-molecular liquid crystal compound specifically usedare shown below. Examples thereof are by no means limited to these.##STR2##

As the polymer liquid crystal compound used in the recording layer ofthe present invention, a ferroelectric polymer liquid crystal compoundis preferred in view of quick response, bistability, and memoryproperty.

The ferroelectric polymer liquid crystal compound usable in the presentinvention may preferably has a chiral smectic phase. It may morepreferably has an SmC* phase, an SmH* phase, an SmI* phase, an SmJ*phase or an SmG* phase.

The ferroelectric polymer liquid crystal compound used may have astructure of a main-chain type, a side-chain type or amain-chain/side-chain type. As the main-chain type ferroelectric polymerliquid crystal compound, it is possible to use those of a polyestertype, a polyether type, a polyazomethine type, a polythioester type, apolythioether type, a polysiloxane type, a polyamide type or a polyimidetype. As the side-chain type ferroelectric polymer liquid crystalcompound, it is possible to use those of a polymathacrylic type, apolyacrylic type, a polychloroacrylic type or a polyether type.

The above main-chain type, side-chain type or main-chain/side-chain typeferroelectric polymer liquid crystal compounds may be used alone, or maybe used by mixture or copolymerization thereof with two or more of thesame type or different type of polymer liquid crystal compound.

Some examples of the ferroelectric polymer liquid crystal compoundusable in the present invention are shown below. Examples thereof are byno means limited to these. ##STR3##

It is also possible to use an optically active polymer liquid crystalcompound capable of rendering ferroelectric properties as a result ofblending or the like.

Such a compound may specifically include the following: ##STR4##

In the present invention, the above ferroelectric polymer liquid crystalcompounds can be used alone or in combination.

In the present invention, a polymeric liquid crystal compositioncomprising the ferroelectric polymer liquid crystal compound and thelow-molecular liquid crystal compound can be used in a ferroelectricpolymer liquid crystal layer. The low-molecular liquid crystal compoundused may preferably be a ferroelectric liquid crystal compound, but neednot be the ferroelectric liquid crystal compound so long as theproperties of the ferroelectric polymeric liquid crystal compound arenot damaged.

Regarding the instance where the low-molecular liquid crystal compoundshows ferroelectric properties, examples of such a compound are alsoshown below. ##STR5##

In the mixture of the ferroelectric polymer liquid crystal compound andthe low-molecular liquid crystal compound, the low-molecular liquidcrystal compound should preferably be contained in an amount of not morethan 40% by weight. An amount more than 40% by weight is not preferablesince film strength or film forming properties may be damaged. It shouldmore preferably be in an amount of not more than 20% by weight.

In aligning the polymer liquid crystal compound, it is possible toutilize the surface effect.

For example, an alignment control film can be provided, which is a filmformed using an inorganic insulating material such as silicon monoxide,silicon dioxide, aluminum oxide, zirconium oxide, magnesium fluoride,cerium oxide, cerium fluoride, silicon nitride, silicon carbide or boronnitride or an organic insulating material such as polyvinyl alcohol,polyimide, polyamidoimide, polyester imide, polyparaxylene, polyester,polycarbonate, polyvinyl acetal, polyvinyl chloride, polyamide,polystyrene, cellulose resin, melamine resin, urea resin or acrylicresin.

This alignment control film can be obtained by forming the inorganicinsulating material or organic insulating material into a film, andthereafter rubbing its surface with velvet, cloth or paper in a givendirection.

In the present invention, the alignment control film can also beobtained by forming a film by oblique vacuum deposition using aninorganic insulating material such as SiO or SiO₂.

Alternatively, after the inorganic insulating material or organicinsulating material as described above has been formed into a film, thesurface of the film may be etched by oblique etching, whereby thealignment control effect can be imparted to its surface.

The alignment control film described above may preferably also functionas an insulating film. For this purpose, the thickness of this alignmentcontrol film may be set within the range of usually 100 Å to 1 μm, andpreferably 500 Å to 5,000 Å. This insulating layer has the advantagethat it can prevent currents that may be caused by impurities containedtherein in a very small amount. Hence, the polymeric liquid crystalcompound is not deteriorated even after repeated operations. Thisalignment control film may be formed in contact with the recording layer105. For example, it may be formed as shown in FIG. 1D, referencenumeral 107.

The polymer liquid crystal compound and the composition comprising it,described above, can be well aligned not only by the aligning methodsdescribed above but also by the following aligning methods. As methodsthat can surely effect molecular alignment, it is preferred to usestretching such as monoaxial stretching, biaxial stretching or inflationstretching or re-alignment by means of shearing. A material having nofilm properties when used alone and for which it is therefore difficultto be stretched, may be sandwiched between films and then stretchedtogether with the films, whereby the desired alignment can be effected.

In the present invention, when the recording layer 105 has a low volumeresistivity, the protective layer 106 as shown in FIG. 1A may beprovided so that it can be prevented from deterioration due to inclusionof ions into the recording layer 105. For this reason, the protectivelayer 106 should have a volume resistivity of not less than 10¹² Ω.cm,and preferably not less than 10¹⁴ Ω.cm, and it is preferred to use epoxyresin, silicone resin, polystyrene, polymethacrylate, polyvinylchloride, polytetrafluoroethylene, etc.

The protective layer should preferably have a thickness of 0.1 μm to 10μm. A thickness less than 0.1 μm and a thickness more than 10 μm are notpreferred since the former may result in an insufficient resistivity andthe latter may cause an expansion of electric fields ascribable tosurface charges.

In the recording medium of the present invention, a light absorbinglayer may be additionally provided. Alternatively, a recording mediumcomprising a recording layer in which a laser light absorbing compoundhas been dispersed or dissolved may be used. In other words, therecording medium should be constituted in the above way when laser beamsare used in the step of heating the recording layer at the state wherean image is formed according to the present invention.

When a display surface is affected by the light absorbing layer or thelight absorbing compound, those having no absorption at the visiblelight region should be used.

The laser light absorbing compound that may be added to the recordinglayer includes, for example, azo compounds, bisazo compounds, trisazocompounds, anthraquinone compounds, naphthoquinone compounds,phthalocyanine compounds, naphthalocyanine compounds,tetrabenzoporphiline compounds, aminium salt compounds, diimonium saltcompounds and metal chelate compounds.

Of the above laser light absorbing compounds, compounds forsemiconductor lasers have an absorption at the near infrared region andare useful as stable light absorbing coloring matters. They also have agood compatibility with or dispersibility in the recording layer. Someof them have a dichroism. Mixing of any of these compounds with adichroism into the recording layer makes it also possible to obtain athermally stable, host-guest type recording medium.

The above compound may be contained in the recording layer incombination of two or more kinds.

The above compound may also be used in combination with a different typeof near infrared absorbing coloring matter or dichroic coloring matter.The neap infrared absorbing coloring matter that can be preferably usedin combination can be typically exemplified by coloring matters such ascyanine, merocyanine, phthalocyanine, tetrahydrocholine, dioxazine,anthaquinone, triphenodithiazine, xanthene, triphenylmethane, pyrylium,croconium, azulene, and triphenylamine.

The above compound may be added to the recording layer in an amount of0.1% by weight to 20% by weight in approximation and preferably 0.5% byweight to 10% by weight.

The image forming method of the present invention will be describedbelow with reference to FIGS. 2A to 2E and 3A to 3E.

FIG. 2A cross-sectionally illustrates a recording medium having aphotoconductive layer 203. A recording layer 204 containing thepolymeric liquid crystal compound should preferably have beenhorizontally aligned when it has Δε>0, and vertically aligned when ithas Δε<0. Reference numeral 201 denotes a substrate film; and 202, alower electrode.

As shown in FIG. 2B, upon overall charging using a corona assembly 205,charges are generated in the lower electrode 202 and on the surface ofthe recording layer 204. At this time, the charging should preferably beat a voltage of 100 V to 8,000 V.

Next, as shown in FIG. 2C, image information is exposed to light usingan exposure assembly 206. This exposure is carried out using light witha wavelength to which the photoconductive layer 203 has a sensitivity,and may be carried out on the whole area by the use of a mask or carriedout by laser beam scanning. As a result of this exposure, the chargespresent in the lower electrode 202 move at an exposed area 208 and cometo exist at the interface between the photoconductive layer 203 and therecording layer 204. This brings about an increase in electrostaticcapacitance at the exposed area.

The movement of charges to the photoconductive layer causes changingbirefringence of the recording layer to change the molecularorientation, so that the writing can be effected.

The molecular orientation as described in the present invention whichbrings a change of the birefringence includes a partial change oforientation of a mesogen that constitutes the polymer liquid crystal. Insome instances, however, depending on the type of the recording layer,it is better to carry out the writing in a heated state by selectingtemperature ranges in which the polymer liquid crystal has a liquidcrystal phase and glass transition points. In a preferred embodiment,from the viewpoints of writing speed and readiness in controllingwriting conditions, the heating is carried out using a heater 207 (athermal head) as shown in FIG. 2E, to cause the molecular orientation tochange.

The heating shown in FIG. 2E is carried out at a temperature set withinthe liquid crystal temperatures.

In a more preferred embodiment, after the step shown in FIG. 2C, thecharging may be repeated as shown in FIG. 2D. This brings about anincrease in electrostatic capacitance, according to which the charges atthe exposed area increase.

The recording medium may be brought into the state as described above,to cause the molecular orientation to change. Alternatively, in thestate as described above, it may also be heated to a temperature higherthan the glass transition temperatures, using the heater 207 as shown inFIG. 2E, to cause the molecular orientation to change to effect writing.

As a means for the heating, the thermal head as shown in FIG. 2E or alaser beam (not shown) may be used.

As a laser beam source, it is preferred to use a gas laser such as anHe--Ne gas laser, an Ar²⁺ gas laser or an N₂ gas laser, a solid lasersuch as a ruby laser, a glass laser or a YAG laser, or a semiconductorlaser. It is also preferred to use a semiconductor laser with awavelength region of 600 nm to 1,600 nm. It is particularly preferred touse a semiconductor laser with a wavelength region of 700 nm to 900 nm.

In the case when the laser beam is used, the light absorbing layer isadditionally provided. Alternatively, the recording medium comprising arecording layer in which a laser light absorbing compound has beendispersed or dissolved is used.

FIGS. 3A to 3E illustrate a process by which a surface electrostaticimage on a photoconductive layer 303 is contact-transferred to arecording layer 306 containing a polymer liquid crystal compound. Thisis a process commonly called TESI (transfer of electrostatic image)process. In the drawings, reference numeral 301 or 301' denotes asubstrate film; 302 or 302', a lower electrode; 304, a corona assembly;305, an exposure assembly; and 307, a power source.

The surface electrostatic image is formed in the manner as shown inFIGS. 3A and 3B, and then, as shown in FIG. 3C, a voltage of 500 V to5,000 V is applied across the lower electrode 302 of the substrateprovided with the photoconductive layer and the lower electrode 302' ofthe substrate having the recording layer 306, in the state of which theboth are brought into contact and then separated, so that the surfaceelectrostatic image can be transferred to the substrate having therecording layer 306.

The transfer of charges causes the birefringence of the recording layerto change, so that the writing can be effected.

In a more preferred embodiment, this substrate having the recordinglayer 306 is heated using a heater 308 to cause the orientation of thepolymer liquid crystal compound to change, so that anorientation-changed area 309 is formed as shown in FIG. 3E.

The recording medium in which an image has been formed by the imageforming method of the present invention is used as the intermediateimage holding medium, and the image is displayed on a screen ortransferred to a photosensitive member. A visible image can be thusobtained.

A photosensitive member suited for the transfer may include thefollowing:

(a) Electrophotographic photosensitive members,

(b) Diazo photosensitive materials,

(c) Silver salt photosensitive materials,

(d) A capsule sheet photosensitive member coated with microcapsules inwhich a photocurable resin and a colorless dye are encapsulated, astypically disclosed in Japanese Patent Application Laid-open No.59-30537.

(e) Photoresist members,

(f) A photosensitive member comprising a material reactive to light andheat, in which, when a heat energy and a light energy are applied, thereaction of the material abruptly proceeds to cause irreversible changesin transfer characteristics to form an image because of differences inthe above characteristics, corresponding with image signals (JapanesePatent Application Laid-open No. 62-174195).

EXAMPLES

The image forming method and recording medium of the present inventionwill be decribed below in greater detail by giving Examples, and alsothe method of reproducing a visible image will be described.

Example 1

In this example, shown is an example in which the image forming methodand recording medium of the present invention are applied to anintermediate image holder used in an electrophotographic image formingprocess.

According to the present example, it is made possible to record imagesat a high speed on plural sheets without use of a laser and a precisionoptical system comprising a polygon mirror, after a process in which,when an initial intermediate image is read in, an optical scanner isdriven in a low speed so that a highly detailed image is read in, andthe intermediate image is thermally taken onto a polymer liquid crystalin accordance with this image information or image information sent froma memory.

This example will be described below with reference to the apparatusshown in FIG. 4.

In the drawing, the numeral 401 denotes a recording medium, which wasprepared in the following way: On a transparent substrate made of glassor the like, a transparent electrode (the lower electrode) was formed ina thickness of 500 Å, and on the transparent electrode a photoconductivelayer comprising amorphous silicon was formed in a thickness of 20 μm.Next, a dielectric mirror was formed thereon by vacuum deposition sothat light with a wavelength of 550 nm can be reflected. A polyimidealigning film was further formed thereon by baking. On the resultingaligning film, a recording layer comprising a horizontally alignedpolymer liquid crystal compound was formed, which was formed in thefollowing way: A polymer liquid crystal compound represented by thefollowing structural formula: ##STR6## was dissolved in dichloroethaneto give a 20% solution, and the above substrate provided with the statedlayers was dipped in (or may be coated with) this solution. Thesubstrate thus coated was left to stand in an oven at 95° C. for 60minutes.

An ultraviolet-curable silicone resin was then applied on the surface,followed by curing with ultraviolet rays.

The recording medium 401 is read with an if radiation optical system 402that is driven in synchronization with an electrophotographic systemshown at the lower part of FIG. 4.

A uniform heating-annealing device 403 is comprised of a halogen heaterand a plane heater, and the halogen heater is set at about 120° C. andthe plane heater at about 85° C.

As the uniform heating-annealing device 403 is moved along the surfaceof the recording layer, the medium is heated to 115° C. by the halogenheater and is turned transparent on substantially the whole area. As itis passed on the plane heater, re-alignment takes place on the wholearea, and an image is thus erased.

Here, the image was recorded according to the process shown in FIGS. 2Ato 2E.

An image production process will be described below.

(a) Initial state:

The recording layer comprising the polymer liquid crystal compound is ina horizontally aligned state. A photosensitive member 405 is in anuncharged state.

(b) As shown in FIG. 2B, the whole areal charging is carried out usingthe corona assembly 205, and the image is exposed to light using anexposure system as shown in FIG. 4 by the numeral 404 and in FIG. 2 bythe numeral 206, where the charges are transported at the exposed area208.

Next, the the recording medium is again charged and then heated andcooled using the uniform heating-annealing device 403 in the same way asin the above, so that the exposed area is vertically oriented to give animage that can be read out.

As for the photosensitive member 405, it is primarily charged using thecorona assembly 410, where negative charges (or positive chargesdepending on processes) are applied.

(c) The irradiation optical system is operated to irradiate therecording medium 401 with linearly polarized light. Light reflectedtherefrom is converged to a selfoc lens 412 through an analyzer 413, andis shed onto the photosensitive member 405 for its exposure.

(d) Corresponding with the charged state on the surface of thephotosensitive member 405, a latent image is developed with a toner bymeans of a developing assembly 406.

(e) The toner on the photosensitive member 405 is transferred to atransfer medium 411 such as paper by means of a transfer device 407. Thetoner on the transfer medium 411 is thereafter fixed by means of afixing device (not shown).

(f) The recording medium 401 is turned into horizontal alignment on itswhole area by means of the uniform heating-annealing device 403, andbrought to the initial state.

The photosensitive member 405, from the surface of which the remainingtoner has been removed by means of a cleaner 408, is subjected to wholeareal exposure by means of a whole areal exposure device 409, so thatthe charges on the surface of the photosensitive member 405 are removed.Thus the photosensitive member 405 is brought to the initial state.

In this way, the toner is adhered to the transfer medium correspondingwith the unexposed area of the recording layer. A negative image is thusobtained. In this example, it was possible to obtain on the transferpaper a clear image with a white-ground density of 1.1.

Example 2

An example in which the image forming method and recording medium of thepresent invention are applied to an intermediate image holder in animage forming process making used of a diazo photosensitive materialwill be described with reference to FIG. 5.

According to this example, it is made possible to directly take a copyfrom a bulky object such as a book, using an image forming apparatusmaking use of an intermadiate image holding method and holder.

In an optical image transfer apparatus shown here, a recording medium501, an exposure optical system 515 and a uniform heating-annealingdevice 503 are the same as those in Example 1. An illuminator 509 is setas an ultraviolet generator. This illuminator may be used to subject thewhole A4 size sheet to flash exposure to effect plane transfer, or slitexposure to effect whole areal transfer.

The recording medium 501 serving as the intermediate image holder, andtransport belts 516 and 517 are synchronizingly driven in the directionof arrows by means of a driving unit (not shown). Reference numeral 502denotes a corona assembly, which corresponds to the one shown in FIG.2B. The recording medium 501 in which information has been recordedusing the exposure optical system 515 is passed through the place atwhich a corona assembly denoted as 504 is provided (corresponding toFIG. 2D), and thereafter brought into close contact at the part "A" witha diazo photosensitive sheet 518 transported there by means of a belt516, where exposure is effected using the illuminator 509.

As the diazo photosensitive sheet, usual sheets commercially availablecan be used. A sheet coated with a mixture of a diazonium salt and acoupler was used here. In this way, an image with a high contrast wasobtained.

Example 3

FIG. 6A shows an example wherein the recording medium of the presentinvention is applied to a system comprising exposing to light thecapsule sheet coated with microcapsules in which a photocurable resinand a colorless dye are encapsulated, as typically disclosed in JapanesePatent Application Laid-open No. 59-30537, to cause the microcapsules toselectively cure, and thereafter breaking the capsules by theapplication of pressure or the like to form an image on a receiver sheetcoated with a resin. In FIG. 6A, the numeral 620 denotes a lasermodulated signal generator; 621, a semiconductor laser; 622 or 622', anf-θ lens; 623, an X-axis scanning mirror (polygon); 624, a Y-axisscanning mirror (galvanomirror); 625, Y-axis scanning lens drive; 626,Y-axis scanning drive signal generator; 627, an objective lens; 628, aprojection lens; 629, a receiver sheet; 630, a pressure transfer unit;631, B(blue)-corresponding light source unit; 632, R(red)-correspondinglight source unit; 633, G(green)-corresponding light source unit; 634, adichroic prism; and 635, a light-source selecting signal generator.Here, the semiconductor laser 621 is modulated and the polygon 623 andthe galvanomirror 624 were used to write intermediate imagescorresponding to R, G and B in the recording medium 601 serving as animage bearing medium. On the intermediate image written in the recordingmedium 601, the R-corresponding wavelength light, G-correspondingwavelength light and B-corresponding wavelength light are successivelyirradiated through the dichroic mirror by means of the light sourceunits, and then the intermediate image formed in the recording medium601 is projected on the photosensitive sheet 605 through the projectionlens 628 to effect exposure. The photosensitive sheet thus exposed issuperposed onto the receiver sheet 629, which are then passed throughthe pressure transfer unit 630, so that an image is fromed on thereceiver sheet 629.

FIG. 6B shows an example wherein the recording medium of the presentinvention is applied to a system comprising applying light and heat to acapsule sheet coated with microcapsules in which aphotocurable-thermosetting resin and a colorless dye are encapsulated,as typically disclosed in Japanese Patent Application Laid-open No.62-174195, to cause the microcapsules to selectively cure or set, andthereafter breaking the capsules by the application of heat and pressureor the like to form an image on a receiver sheet. In FIG. 6B, thenumerals 620 to 635 denote the same as those in FIG. 6A. The numeral636a denotes a plane heating element drive unit; 636b, a plane heatingelement; and 637, pressure-heat transfer unit. The writing of anintermediate image and the irradiation from the light source unit arecarried out in the same way as in the example shown in FIG. 6A. Insynchronization with the irradiation of the R-corresponding wavelengthlight, G-corresponding wavelength light and B-corresponding wavelengthlight, the photosensitive member is heated by means of the plane heatingelement, and the intermediate image formed in the recording medium 601is projected on the heated portion to effect exposure. Thephotosensitive sheet thus exposed is superposed onto the receiver sheet629, which are then passed through the pressure-heat transfer unit 637,so that an image is fromed on the receiver sheet 629.

Example 4

FIGS. 7A and 7B illustrate apparatus for carrying out flood exposure toR-, G- and B-corresponding wavelength light rays, using thephotosensitive members used in Example 3, shown in FIGS. 6A and 6B,respectively.

In FIGS. 7A and 7B, the numerals 701, 705, 728, 729, 730, 736a, 736b and737 correspond to the numerals 601, 605, 628, 629, 630, 636a, 636b and637 in FIG. 6, respectively. The numeral 738 denotes a light sourceunit; 739(a), 739(b) and 739(c) each, a dichroic mirror; and 740, adichroic prism.

Example 5

FIGS. 8A and 8B each show an example in which a projection opticalsystem comprises a combination of a polarizer 81 and an analyzer 82.FIG. 8A shows an example in which a transmission type recording medium83 is used, and FIG. 8B shows an example in which a reflection typerecording medium 84 is used. In both examples, higher values than thosein Example 3 were each obtained as a contrast on a sheet (aphotosensitive member) 85. The sheet 85 may be comprised of a merescreen. Projection on the screen enabled display in a high contrast.

Example 6

FIGS. 9A and 9B each schematically illustrate a recording mediumprojection apparatus making use of a Schlielen optical system. FIG. 9Ashows an example in which a transmission type recording medium 93 isused, and FIG. 9B shows an example in which a reflection type recordingmedium 94 is used. In the drawings, the numeral 91 denotes a Schlielenlens; 92, a light source; 96, a mask; and 97 a projection lens. In bothexamples, higher values than those in Example 3 were each obtained as acontrast on a sheet (a photosensitive member) 95. When a polarizer andan analyzer are used in the above Schlielen optical system, it ispossible to obtain a much higher contrast. The sheet 95 may be comprisedof a mere screen. Projection on the screen enabled display in a highcontrast.

Example 7

    ______________________________________                                        Heat-diffusible dye        1.8    parts                                       Oplas Red 330 (trade name; available from Orient                              Chemical Industries, Ltd.)                                                    Methyl methacrylate/butyl methacrylate copolymer                                                         1.0    part                                        Methyl ethyl ketone        10     parts                                       3,3'-Carbonylbis(7-methoxycoumarine)                                                                     0.16   part                                        Ethyl p-dimethylaminobenzoate                                                                            0.04   part                                        Pentaerythritol tetraacrylate                                                                            2.0    parts                                       ______________________________________                                         part(s): part(s) by weight                                               

The above mixture was weighed out and dissolved using a paint shaker togive a coating solution.

A 6 μm thick polyester film was coated thereon with the above coatingsolution using an applicator so as to give a dried coating thickness of2 μm. A polymerizing layer was thus provided, and a 3 μm thick polyvinylalcohol (PVA) layer was further provided on that polymerizing layer.

On the photosensitive member thus prepared, an intermediate image holdercomprised of the recording medium of the present invention on which animage had been held was superposed, followed by exposure to form alatent image.

A fluorescent lamp having a fluorescent peak at 390 nm was used as alight source, and the exposure was carried out for 1 second, setting thelight source 5 cm distant from the recording material layer.

Thereafter, the intermediate image holder was removed, and the abovephotosensitive member was passed in 8 seconds through a thermaldeveloping machine. The photosensitive member thus processed was furtherput on a hot plate heated to 60° C., which was then irradiated for 60seconds with light from a fluorescent lamp having a fluorescent peak at390 nm, with a distance of 5 cm.

Subsequently, the PVA film was removed. Using as an image receivingmedium a synthetic paper on which an image receiving layer had beenformed with a polyester resin, the photosensitive member and the imagereceiving medium were put together in such a way that the former'spolymerizing layer and the latter's receiving layer faced to each other,followed by heating from photosensitive member side under conditions of120° C. and 10 seconds so that a dye was diffusion-transferred from thepolymerized layer to the image receiving layer. As a result, a sharp redcolor image corresponding with imagewise exposed areas was obtained onthe image receiving layer. The above processing was carried out in adark room on the whole.

Example 8

To 10 parts by weight of methyl ethyl ketone, 1.0 part by weight ofpolymethyl methacrylate, 2.0 parts by weight of Unideck 16-824 (tradename; available from Dainippon Ink & Chemicals, Incorporated), 0.2 partby weight of camphorquinone, 0.1 part by weight of ethylp-dimethylbenzoate, 0.2 part by weight of FORON brilliant scarlet SRG(available from SANDOZ Co.) were added, and the mixture was dispersedusing a paint shaker to give a coating solution.

A polyethylene terephthalate film vacuum-deposited with aluminum(available from PANAK Kogyo K.K.) was coated with the above coatingsolution (an emulsion) using an applicator so as to give a dried coatingthickness of 2 μm. A transparent polyethylene terephthalate film wasprovided thereon in laminae to give a photosensitive member.

Image formation

On the photosensitive member thus prepared, an intermediate image holdermaking use of the recording medium of the present invention wassuperposed, followed by exposure to form a latent image.

A 15 W fluorescent lamp having a fluorescent peak at 390 nm was used asa light source, and the exposure was carried out for 10 seconds, settingthe light source 5 cm distant from the image forming member.

Thereafter, the intermediate image holder was removed, and thetemperature was adjusted to 100° C. The image forming member was thenput on a hot plate heated to 60° C., and exposure was carried out for 20seconds, setting a 380 nm, 15 W fluorescent lamp 5 cm distant from themember.

While the member thus processed was passed through rollers underapplication of heat and pressure at 60° C. and 25 kg/cm², respectively,the transparent polyethylene terephthalate film was peeled. As a result,a red negative image was formed on the film.

In the examples described above, a heat energy is used as the means forrecording an image in the recording layer of the recording medium andlight is used as the means for transferring the image to thephotosensitive member, and hence an excellent durability can beachieved. Incorporation with an ultraviolet absorbent can also bringabout an increase in light resistance.

Besides, using a similar method, it is also possible to transfer anoptical image to silver salt photosensitive materials, dry-system silversalt photosensitive materials, photopolymer members such as photoresistmembers. This enables application of the present invention to theproduction of block copies.

Use of the recording medium as a microfilm makes it possible to copy outimages by an electrophotographic system.

In the present examples, described are instances in which the recordingmeans, erasing means, etc. are put together in one apparatus. Thetechnical idea of the present invention is by no means limited to suchinstances, and includes embodiments in which they are set in cartridges,or separated into two processes.

As having been specifically shown in the above examples, the informationon the recording medium according to the present invention can berapidly rendered visible by projecting it through an analyzer anddisplay it on a screen or transferring it on a photosensitive member,and yet can be faithfully reproduced without any deterioration comparedwith the original image.

Example 9

The same experiment as Example 1 was carried out using the samerecording medium as used in Example 1 except that the recording layerwas replaced with the following one. A sharp image was obtained as aresult of the reproduction. Recording layer:

The polymeric liquid crystal compound described in Example 1: 80% byweight.

The low-molecular liquid crystal compound of exemplary compound I-20:20% by weight.

Example 10

On a substrate provided with the same photoconductive layer comprisingamorphous silicon and the same dielectric mirror as in Example 1, alow-temperature baking polyimdie (HL-1110; available from HitachiChemical Co., Ltd.) was spin-coated followed by baking to form a 500 Åthick aligning film, which was then monoaxially oriented by rubbing.

To the polymeric liquid crystal of the exemplary compound (52)previously set out (x=y=0.5; Mn measured by GPC: 8430; Mw: 18,560;##STR7## the low-molecular liquid crystal of the exemplary compound I-27previously set out was added in an amount of 15% by weight to form arecording layer.

Using a recording medium comprising the above recording layer, the sameexperiment was carried out in the same manner as in Example 1. It wasconfirmed that a sharp image was obtained.

In the present example, the erasure was effected by applying an electricfield reverse to that for writing.

As having been described above, the present invention can provide animage forming method using a recording medium having a recording layerin a film form, and a method in which a pair of electrodes is used and avoltage is not applied therebetween continuously, then according to thepresent invention, image recording method capable of achieving a stablerecording performance, a good memory performance and a high contrast canbe provided, and makes it easy to provide a photosensitive apparatusthat can promise a light load to semiconductor lasers, optical scanners,etc.

What is claimed is:
 1. An image forming method, comprising the stepsof:forming electric charges on a recording layer by charging a recordingmedium which comprises in this order a conductive substrate providedwith a photoconductive layer and a recording layer containing apolymeric liquid crystal compound having a glass transition temperaturehigher than room temperature by moving a corona assembly above saidrecording layer, said recording medium being charged only when imagesare being formed in said recording layer; after forming said electriccharges, irradiating said recording medium with a light corresponding toimage information so as to move electric charges to said photoconductivelayer; again charging the recording medium by relatively moving a coronaassembly with respect to the recording layer; and writing said imageinformation into said recording layer by heating said recording layercausing a change in the birefringence of the recording layercorresponding to said movement of electric charges.
 2. The image formingmethod according to claim 1, wherein said recording layer is furtherprovided thereon with a surface protective layer.
 3. The image formingmethod according to claim 1, wherein said recording medium is furtherprovided with a dielectric mirror.
 4. The image forming method accordingto claim 1, wherein said recording layer is a recording layer containinga polymeric liquid crystal compound and a low-molecular liquid crystalcompound.
 5. An image reproducing method comprising the stepsofirradiating light on the recording medium in which an image has beenformed by the image forming method according to claim 1; and displayingthe image information on a screen or transferring the image informationto a photosensitive member.
 6. The image reproducing method according toclaim 5, wherein heating is carried out at the step of writing.
 7. Theimage reproducing method according to claim 5 or 6, which method furthercomprises a step of re-charging after the step of irradiating therecording medium with a light corresponding to an image information tomove electric charges to said photoconductive layer, and a step ofchanging the birefringence of said recording layer after saidrecharging.
 8. The image reproducing method according to claim 5,wherein said recording layer is further provided thereon with a surfaceprotective layer.
 9. The image reproducing method according to claim 5,wherein said recording medium is further provided with a dielectricmirror.
 10. The image reproducing method according to claim 5, whereinsaid recording layer is a recording layer containing a polymeric liquidcrystal compound and a low-molecular liquid crystal compound.